As medium processing devices, there are image recording devices, such as printers, photocopy machines, facsimile machines, MFPs and the like, that include a function to print an image on a sheet. The term, “MFP” stands for a multi function peripheral, which is a printer with a facsimile function, a scanner function, a copy function and the like.
The image recording device generally includes therein a sheet cassette that stores media (hereinafter referred to as “sheets”) on which an image is recorded. The sheet cassette is configured to be removable from the image recording device so as to facilitate supplementing of the sheets, switching to a different size of sheets and the like.
For the image recording device, it is preferable that the frequency of supplementing sheets, switching a different size of sheets and the like to the sheet cassette be reduced. Therefore, as a sheet supply device that supplies sheets to the image recording device, multi-level trays have been proposed that include sheet cassettes installed in multi-levels in the image recording device (see Japanese Laid-Open Patent Application No. 2006-124058).
Each tray includes a sheet cassette as a storage part that stores sheets, a sheet supply roller as a sheet supply part that supplies sheets from the sheet cassette, a carrying roller as a carrying part that carries the sheets to subsequent parts, a carrying motor as a drive source that drives the sheet supply roller and the carrying roller, a sheet supply clutch as a sheet supply transmission member that selectively transmits a drive force to the sheet supply roller, a carrying clutch as a carrying transmission member that selectively transmits the drive force to the carrying roller, and a controller that selectively operates each of the motor and clutches.
By receiving electricity from the image recording device to drive the carrying motor, each tray selectively performs one of a sheet supply operation (hereinafter referred to as a “first operation”) in which the sheets stored in the sheet cassette are separated and in which each sheet is supplied to subsequent mechanisms, and a carrying operation (hereinafter referred to as a “second operation”) in which a sheet supplied from another tray is carried to the subsequent parts.
As explained below, the conventional sheet supply devices (multi-level trays) have a problem that entire electricity consumption by the image recording device and all sheet supply devices (multi-level trays) (hereinafter referred to simply as “entire electricity consumption”) increases when there is a sheet supply device that performs only the second operation (carrying operation of sheets supplied from another tray) in a state where a plurality of sheet supply devices are installed in the image recording device.
For instance, when multi-level trays with four or more levels are installed, and when a sheet is supplied from the fourth level tray, a sheet supply command is output to the fourth level tray, and a carrying command is output to the first to third level trays. In response, the fourth level tray separates the sheets stored in the sheet cassette piece by piece and feeds each sheet to the subsequent parts (here, the first to third level trays and the image recording device), and the first to third level trays carry the sheet to the subsequent mechanisms.
At this time, the image recording device supplies electricity for supplying and carrying the sheet (i.e., electricity for operating the carrying motor, sheet supply clutch and carrying clutch) to the fourth level tray, and electricity for carrying the sheet (i.e., electricity to operate the carrying motor and carrying clutch) to the first to third level trays.
Therefore, the image recording device needs to supply electricity for operating the carrying clutch to all of the trays, when a plurality of sheet supply devices are installed in the image recording device and when there are sheet supply devices that perform only the second operation. Therefore, the multi-level trays increase the entire electricity consumption.
In addition, the image recording device needs to use a large capacity power source unit to supply electricity for operating the carrying clutch to all sheet supply devices (here, multi-level trays). Therefore, for the conventional sheet supply devices (multi-level trays), it is necessary to increase the size of the power source unit provided in the image recording device. As a result, the conventional sheet supply devices (multi-level trays) have a problem that miniaturization of the image recording device and lowering cost are prevented.
Therefore, the inventors has considered that, when a plurality of sheet supply devices (multi-level trays) are installed in the image recording device, and when there is a sheet supply device that performs only the second operation (operation to carry a medium supplied from another sheet supply device to subsequent mechanisms), the entire electricity consumption is decreased when the sheet supply device that performs only the second operation rotates the carrying roller without receiving a supply of electricity for carrying the sheet (i.e., without operating the carrying clutch).
The present application is provided to solve the above-described problems and has a principle object to provide a supply device that reduces electricity consumption when a medium supplied from another sheet supply device is carried to subsequent mechanisms.